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1. find the values of k.
{ x^2 - 4y^2 + 20 = 0
{ x + 3y + k = 0
2. solve the following equations.
3x - 開方2x+1 = 9 <-- (成個 2x+1 開方)
3. solve the following simultaneous equations using the algebraic method.
{ x^2 + y - x = 1
{ 2x + 3y = 1
answers :
1. k = +5 or -5
2. x = 4
3. ( -1/3 , 5/9 ) , ( 2 , -1 )
thank you !
F.4 數學題 ( 急! )
2008-08-24 5:53 am
回答 (1)
2008-08-24 9:26 am
✔ 最佳答案
2. 3x-√(2x 1)=9
3x-9=√(2x 1)
(3x-9)^2=(√(2x 1))^2
9x^2-54x 81=2x 1
9x^2-56x 80=0
X=4 or 2.2222.....
when x=2.222222...
LHS=3(2.22222)-√(2．2.222222) 1
=4.3333333
when x=4
LHS=3(4)-√(2．４）＋１
=9
so x=4
2008-08-24 01:31:58 補充：
when x=2.222222...
LHS=3(2.22222)-√(2．2.222222) 1
=4.3333333
=/=9(rejected)
收錄日期: 2021-04-29 22:01:21
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